Method of preparing rust-resisting iron and steel printing plates



Aug. 21, 1928; 1,681,849

R. FRITSCHE METHOD OF PREPARING RUST RESISTING IRON AND STEEL PRINTING PLATES Filed April 7. 1927 Z WASHED BY AN ALKALINE SOLUTION ssmsmvE PHOTOGRAPIC SOLUTION INVENTOIR Rudolf Frvtsche BY @M.

ATTOR NEY Patented Aug. 21, 1928.

"UNITED STATES PATENT OFFICE.

armour rnrrsomi, or mrw YORK, n. r. uirrnon or rename nusr-misrerme men um srnnr. rmm'me nurse Application filed April 7, 1827. Serial No. 181,774.

This invention relates to reducing lithogra hic plates using either t e photographic met 0d, the drawing or transfer method, and has for an object to provide improved steps for producing a superior plate through the use of rust resisting iron, steel or similar metal.

Another ob'ect is to provide improved steps in the metho of using rust resisting iron alloy which will not corrode appreciably the water or many chemicals.

A further object of the invention is to provide an improved method and also finished plates for lithographing, wherein the improved steps include preparing a rust res1sting iron and steel plate so as to readily receive the photographic coating or to readily receive and hold in place a transfer or a fatty hand drawing.

In the accompanying drawing- Figure 1 is a plan view of a substantially rust-proof plate showing the formation of the plate greatly exaggerated, after the same has been washed by an alkaline solution.

Figure 2 is a sectional view through Figure 1., approximately on line 2-2.

Figure 3 is a view similar to Figure 2 but showing a sensitive photographic coating applied and ready to receive the photographic impression.

Figure 4 is a View similar to Flgure 2 but showing a modified form of plate produced by washing the plate with a different solution than that shown in Figure 2.

Fi ure 5 is a view similar to Figure 4 but showing a hand drawing and transfer aplied.

P Figure 6 is a view similar to Figure 5, but showing the plate with a protecting coating of any well known kind, as for lnstance, a gum arabic solution. I

Figure 7 is a perspective view of the structure shown in Figure 6, with half of the gum arabic solution removed.

Referring to the accompanying drawing by -numerals, 1 indicates a metal plate, which may be a suitable form of rust resisting iron or steel, such as chrome iron alloy, silicon iron alloy and molybdenum iron alloy. After the plate 1 has been secured, the same is washed with a solution for removing all grease and dirt so as to make the plate clean. A desired solution is ten per cent alkaline solution of a sodium (carbonate of soda) or potassium salt (carbonate of t ash). A ten er cent solution is prefera Is as it secures t e desired repores 2 are formed. In the drawing, these indentations and also the grain, have been greatly exaggerated as in a full size plate these indentations are so small that to the ordinary touch, the surface of a plate would feel smooth. After the plate 1 has been treated until it appears as shown in FigureQ, a sensitive coating 3 is applied thereto, said coating being any desired photographic coating now commonly used After this coating has been applied, the plate is ready to be used in the usual manner in photolithographing. It

is to be understood that the picture is photo-.

graphed directly on the solution 3 and then the solution is subjected to a developing or washin 4 operation in a well known manner, after w ich, the plate is used in printing in a well known manner.

During the printing operation as heretofore carried out with zinc and aluminum plates, there was considerable wearing away of the plates caused by the water commonly used in printing and the chemicals in the printing solution. This Wearing away of the zinc plates was reall' a slow etching which caused the lines of t e work on the plate to become weaker so that the plate, after a certain usage, would make a poor reproduction so that a new plate was necessary if a large number of copies were to be printed.

In printing with the plate 1 as shown in Figure 3, the water and chemicals used in the printing ink, will not affect plate 1 and, consequently,-a very clear print is made and also a large number of prints may be made from the same plate.

In Figures 4 to? inclusive, a modified form of the invention is shown, wherein the plate 1' is identical with the plate 1 except that ydrochloric acid and one art nitric acid.

., If desired, instead of this so ution, a ten ercent solution of hydrofluoric acid coul be used. A stronger solution could be used of this kind up to a concentrated acid by reducing the time of treatment. Sometimes it is of advantage to use these two different solutions in succession and then wash and dry the plate. These treatments result in a plate as shown in Figure 4 which has a grained surface produced in the usual manner of graining and a porous surface to a certain limit, which causes the surface to be sensitive to fatty drawings or transfer impressions. The transfer impression may be placed in osition in the usual 'manner as shown in igure 5 so that the coating 3 will adhere firmly to the plate 1 and the supportlng paper or other material 4 ma be stripped ofi'. The coating 5 is placed on t e prepared surface by a pen or other instrument in the usual manner and may be a solid coating as shown in the drawing or may be in outline or partly in outline and partly solid. After the coatings 3 and 5 have been placed in position, the surface of the plate is then subjected to a coating of a gum arabic solution which will cover the entire surface of plate 1 except where the coatings 3 and 5 are positioned. This gum arabic coating 6 as shown in Figures 6 and 7 causes the entire surface to be a smooth even surface. When the inking roller is passed over the plate in the usual manner, ink will adhere to the coatings 3 and 5 so that a desired print may be secured. After the plate has been prepared as shown in Figures 6 and -7, it is in condition for printing in the usual press and in the usual manner. The only difference in printing, is that the'plate is not injured by the water or chemicals in the printing ink and, consequently, many prints may be secured from the same plate and all of the prints will show a clear lmpresslon.

What I claim is: a

I. A litho raphic plate, comprising a chrome steel ody formed with graining on one surface, with said grained surface having a porous formation.

2. The method of preparing a photolithographic plate, comprising the provision of a chrome steel plate, graining said plate,-washing the plate with a solution of carbonate of potash until all grease and free dirt are removed, washin said late with water until the alkaline so ution as been all removed, drying said late, and finally coating tlie plate with a D otographic coating. i

3. The method of producing a lithographic plate, comprising the production of a chrome steel plate, graining said plate, washing said plate with a 10% solution of carbonate of potash until the surface is somewhat porous, washing said plate with water until the solution has been all removed, and finally drying the plate.

4.-The method of preparing lithographic plates, consisting in Washing a rust-proof chrome steel plate to make the same sensitive to fatty drawings and transfer impressions, the washing being performed by a five to twenty-five per cent solution of a mixture of three parts hydrochloric acid and one part nitric acid, washing said solution off said plate by water, and finally drying the plate.

5. The method of forming a lithographic plate, consisting in providing a rust-proof chrome steel plate, washing one surface of the plate with a ten per cent solution of hydrofluoric acid, washing said acid off said plate with water, and finally drying the plate.

6. The method of forming a lithographic plate, consisting in providing a rust-proof chrome steel plate, making the surface of said plate sensitive tofatty drawings or transfer impressions by Washing said surface With first a five to twenty-five per cent solution of mixture of three parts hydrochloric acid and one part nitric acid, and then washing the surface with a ten percent solution of hydrofluoric acid, washing the various acids from the plate by the use of Water, and finally drying the plate.

RUDOLF FRITSCHE. 

